How are matrices used in cryptography? - Answers

Suppose you had a secret message you needed to give someone. You can use a matrix to make it unreadable to anyone except the recipient. First, you must have an encoding matrix. Let's suppose your encoding matrix is... -2 2 3 -1 3 2 2 1 3 And your message is... I like matrices You must then write you message with numbers. Suppose you use the code A=1, B=2, C=3 etc. Spaces are 27. That would make your message this: 9 27 12 9 11 5 27 13 1 20 18 9 3 5 19 You translate this into a matrix, going down the columns. The matrix must have three rows to be able to multiply. 9 9 27 20 3 27 11 13 18 5 12 5 1 9 19 When you multiply the two, you get... 72 19 -25 23 61 96 34 14 52 50 81 44 70 85 68 To find the original message, you multiply by the inverse of the encoding matrix--the decoding matrix. You will find the first pattern of numbers and be able to find the message. (Sorry, I don't know how to make matrix brackets. You'll just have to deal with it. I tried to make it pretty clear.)